The function of 100% O2 suction key in Bennett 7200 microprocessor ventilator

Tracheal suctioning of a patient on a ventilator may induce hypoxemia. Bennett 7200 microprocessor ventilator has an "100% O2 suction" key which is claimed to provide 100% oxygen for two minutes and switch back automatically when this function is set. Four 7200 ventilators were tested to verify this function. We found that the mean lag time varied from 20.1 seconds to 103.3 seconds and the mean recovery time varied from 33.0 seconds to 134.6 seconds according to the difference of initial tidal volume, ventilator rate and fractional inspired oxygen setting. When the ventilator was on "100% O2 suction", the delivered tidal volume was less than the preset tidal volume. In order to hyper-oxygenate and hyper-inflate the patient to prevent suction-induced hypoxemia, those finding should be taken into consideration when the clinicians apply this function in clinical situation.